JP2019123149A - Thrust washer injection mold - Google Patents

Abstract

To be able to omit a process of removing a disk gate such as lathe processing after injection molding while employing the disk gate.SOLUTION: An injection mold 1 is a mold for injection molding a synthetic resin through a disc gate in an annular cavity 5 formed by abutting a fixed mold plate 3 and a movable mold plate 2. The movable mold plate 2 has a ring-shaped recess 2a and a core pin 7 disposed on a central axis of the recess 2a. The fixed mold plate 3 has an insert 10 having an end face facing the recess 2a and a sprue bush 11 coaxially disposed with the core pin 7 at center axis of the insert 10. An outer peripheral shape of the core pin 7 and an outer peripheral shape of a surface of the sprue bush 11 facing the core pin 7 have the same shape. The disc gate 6 is formed between the core pin 7 and the sprue bush 11, and in an abutting state, the sprue bush 11 can be retracted from a PL and the disc gate 6 can be cut by advancing the core pin 7.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an injection mold of a hollow disk-shaped thrust washer.

  A hollow disc-like thrust washer made of synthetic resin is lighter than a metal rolling thrust bearing and has advantages such as downsizing, corrosion resistance, and low cost. For example, it is similar to the Bearly TW series (manufactured by NTN Precision Resins Co., Ltd.) It is marketed as a thrust washer. The Barely TW series is made of a resin composition based on polytetrafluoroethylene (PTFE) resin, and is manufactured by entire surface machining from a rod-like or pipe-like compression molded body.

  In parts, devices, and machines in which the thrust washer is incorporated, the thrust washer is often limited in shape due to the design balance with other members. For example, a part of the outer peripheral surface may be cut in a straight line to provide a detent function, the outer peripheral shape may be matched to the housing shape, or a lubricating groove may be provided on the sliding surface. The thrust washer is manufactured by the injection molding with respect to such a request | requirement (refer patent documents 1-3).

JP, 2002-139027, A JP, 2016-176539, A Japanese Patent Application Laid-Open No. 06-193628

  The thrust washer of Patent Document 1 is formed by being filled with a resin composition from a film gate having a circumferential length of 1/6 to 1/2 of the outer circumferential length. By injection molding using this film gate, the influence of molding shrinkage can be reduced, and a thrust washer having high accuracy in the thrust direction and high roundness can be obtained. However, in this manufacturing method, since welds, which are regions where molten resins merge, occur, there is a concern that the strength of the molded body may be reduced.

  The thrust washer of Patent Document 2 uses a polyamide resin composed of a dicarboxylic acid component and a diamine component as a base resin, and the composition obtained by blending a fibrous reinforcing material with this polyamide resin enhances the strength of the weld. However, even with this manufacturing method, there is a concern that the surface smoothness of the weld may be reduced since weld occurs.

  On the other hand, the thrust washer of Patent Document 3 is obtained by injection molding using a disk gate. Since welding does not occur in the disc gate type injection molding, it is possible to prevent strength reduction and surface smoothness deterioration due to welding. However, in this injection molding, it is generally necessary to cut the inner diameter portion of the molded body after the injection molding. Cutting of the inner diameter portion is removal of the disk gate, and lathe machining as a separate process is indispensable after injection molding, which causes the increase of manufacturing time and cost increase.

  The present invention has been made to address these problems, and it is an injection mold for a thrust washer that can dispense with a disc gate removal process such as lathing after injection molding while adopting a disc gate. Intended to be provided.

  The injection mold of the thrust washer according to the present invention is a hollow disc-shaped thrust washer injection mold of a three-plate mold structure comprising a movable mold plate, a fixed mold plate and a runner stripper plate, The mold is a mold for injection molding a synthetic resin into an annular cavity formed by abutting the fixed mold plate and the movable mold plate through a disc gate provided on the inner peripheral portion of the cavity. The movable mold plate includes an annular recess which constitutes a part of the cavity, a core pin concentric with the recess, which is disposed on a central axis of the recess, and a central pin on the core pin And the fixed mold plate is disposed flush with the abutment surface with the movable mold plate, and has a nested face having an end face that constitutes a part of the cavity, facing the recess. And the above nesting center And having a sprue bush coaxially arranged with the core pin, and the outer peripheral shape of the core pin and the outer peripheral shape of the surface of the sprue bush facing the core pin have the same shape, and the fixing The disc gate is formed between the core pin and the sprue bush in an abutting state in which the mold plate and the movable mold plate abut, and in the abutting state, the sprue bush recedes from the abutting surface It is characterized in that the disk gate can be disconnected by advancing the core pin.

  In the abutting state, the core pin is advanced in the mold closing direction, and the sprue bush is retracted.

  The fixed mold plate is characterized in that it has limiting means for limiting the backward distance of the sprue bush in the abutting state.

  The limiting means is a columnar member having a main body portion and a flange portion expanded in diameter from the main body portion, and the fixed mold plate has a housing portion for housing the limiting means, and in the housing portion, The restricting means is accommodated so as to be movable in the mold closing direction interlocking with the backward movement of the sprue bush, and the end face on the mold closing direction side of the flange portion abuts on the accommodating portion with the movement of the restricting means. Therefore, the backward distance of the sprue bush is limited.

  The core pin is advanced at the same time as the runner stripper plate and the stationary mold plate are released.

  The injection mold of the thrust washer according to the present invention is a synthetic resin through a disk gate provided on the inner peripheral portion of an annular cavity formed by abutting a fixed die plate and a movable die plate. Since it is a mold for injection molding, welding does not occur. Therefore, it is possible to prevent strength reduction and surface smoothness reduction due to welding, and to be excellent in uniformity of strength and surface smoothness. In addition, it is possible to prevent the surface smoothness of the gate from being lowered when using a limiting gate such as a side gate or a pin gate, and the surface smoothness is excellent. In addition, because of the three-plate mold structure, the molded product and the runner portion can be separated and taken out, and the manufacturing efficiency can be improved.

  Furthermore, the movable template has an annular recess that constitutes a part of the cavity, and a core pin disposed on the central axis of the recess, and the fixed template faces the recess to form a part of the cavity. An outer peripheral shape of the core pin and an outer peripheral shape of a surface opposite to the core pin of the sprue bush, having a nest having an end face to be configured and a sprue bush disposed on the central axis of the nest and coaxially with the core pin In the same shape, the disc gate is formed between the core pin and the sprue bush in the abutting state, and in the abutting state, the sprue bush is retractable from the abutting surface, and the disc gate is cut by the advancement of the core pin. It is possible. That is, since the injection molding die of the present invention can be gate-cut in the mold, it is possible to omit the process of removing the disk gate such as lathe after injection molding. The omission of the manufacturing process can shorten the manufacturing time and reduce the manufacturing cost.

  The fixed template has limiting means for limiting the retraction distance of the sprue bush in the abutting state. The backward distance of the sprue bush corresponds to the forward distance of the core pin, and the longer the backward distance of the sprue bush, the longer the forward distance of the core pin. In this regard, by limiting the above-mentioned retraction distance by the limiting means, the advancement distance of the core pin is also limited, and the load on the core pin can be reduced during the advancement.

  Further, the restricting means is accommodated so as to be movable in the mold closing direction interlocking with the backward movement of the sprue bush, and the end face on the mold closing direction side of the flange portion abuts on the accommodating portion with the movement of the restricting means. Since the retraction distance of the bush is limited, it is possible to limit the retraction distance while making a simple mold structure.

  Further, since the core pin is advanced at the same time as the stripper plate and the fixed mold plate are opened, generation of burrs at the gate cut portion can be prevented.

It is sectional drawing which shows the structure of the injection mold of this invention. FIG. 2 is a partially enlarged view of the periphery of a disk gate of the mold of FIG. 1; It is a partially expanded view of the stop bolt periphery of the metal mold | die of FIG. It is a cross-sectional schematic diagram which shows the filling process using the metal mold | die of this invention. It is a cross-sectional schematic diagram which shows the runner part taking-out using the metal mold | die of this invention. It is a cross-sectional schematic diagram which shows the gate cut process using the metal mold | die of this invention. It is a cross-sectional schematic diagram which shows the mold release process using the metal mold | die of this invention. It is a perspective view showing one form of a thrust washer.

  One embodiment of the hollow disk-shaped thrust washer obtained by the injection molding die of the present invention will be described based on FIG. FIG. 8 is a perspective view of a thrust washer. As shown in FIG. 8, the thrust washer 31 is a hollow disk-like (annular flat plate-like) member and has an inner diameter connecting the thrust surface 31a, the thrust surface 31b which is the opposite surface, and both the thrust surfaces 31a and 31b. It has a surface 32 and an outer diameter surface 33. The two thrust surfaces 31a, 31b are planar in shape and serve as sliding surfaces with the other member. The inner diameter surface 32 and the outer diameter surface 33 are each formed in a substantially cylindrical shape. The thrust washer 31 also has a notch 34 in which a part of the cylindrical outer diameter surface is cut in a straight line. The notch 34 has a locking function, and by engaging the notch 34 with the housing, relative rotation of the thrust washer 31 with respect to the housing can be prevented. The shape of the outer diameter surface of the thrust washer 31 is not limited to a substantially cylindrical shape, and may be a polygonal shape in accordance with the housing shape.

  In the embodiment of FIG. 8, the thrust washer 31 has a plurality of (four) radial grooves 35 on the thrust surface 31a. The plurality of grooves 35 are provided at equal angular intervals from one another at the disk center angle. The grooves 35 are formed on the thrust surface as concave portions penetrating from the inner periphery to the outer periphery of the disk. When the groove is incorporated into a device or the like, this groove becomes a lubricating groove, and the supply of lubricating oil to the flat portion is improved. The thrust washer 31 is not limited to the one shown in FIG. 8; it may have a groove on both thrust surfaces 31a and 31b, or it may have no groove on either of the thrust surfaces 31a and 31b. Further, the number and shape of the grooves in the thrust surface on one side are not particularly limited.

  The size (thickness, outer diameter, inner diameter, width, etc.) of the thrust washer 31 manufactured by the manufacturing method of the present invention is appropriately set depending on the application and the like. For example, the thrust washer 31 has a thickness of 0.2 mm to 8 mm, an inner diameter of 10 mm to 60 mm, and an outer diameter of 20 mm to 160 mm.

  The injection mold for the thrust washer of the present invention is a mold for manufacturing the above-mentioned thrust washer. This injection molding die will be described based on FIG. FIG. 1 is a cross-sectional view showing an example of the injection mold of the present invention. As shown in FIG. 1, the injection molding die 1 is a die having a three-plate structure including a movable die plate 2, a fixed die plate 3 and a runner stripper plate 4.

  The injection molding die 1 is provided in an annular cavity 5 formed by abutting the movable die plate 2 and the fixed die plate 3 via a disc-shaped disc gate 6 provided on the inner peripheral portion of the cavity 5. It is a mold for injection molding a synthetic resin. The cavity 5 is formed such that the axial direction of the molded body (thrust washer) and the mold closing / mold opening direction of the mold coincide with each other. In the present invention, the “mold closing direction” is a direction in which the fixed mold plate and the movable mold plate approach the runnaper stripper plate, and is the right direction in FIG. The “mold opening direction” is a direction in which the fixed mold plate and the movable mold plate are separated from the runner stripper plate, and is the left direction in FIG. Also in FIGS. 2 to 7, the right direction of each drawing corresponds to the mold closing direction, and the left direction of each drawing corresponds to the mold opening direction.

  FIG. 1 shows the injection molding die 1 before injection molding, in which each die is closed. In this case, the movable mold plate 2 and the fixed mold plate 3 are abutted at the parting line PL, and the fixed mold plate 3 and the runner stripper plate 4 are abutted at the abutting surface F. As described later, the abutment surface F is opened to take out the runner part after the forming process, and the parting line PL is opened to take out the thrust washer and the disk gate part after the forming process.

  In the movable mold plate 2, an annular recess 2 a is formed on the end surface of the parting line PL. The recess 2 a constitutes a part of the cavity 5 and forms one thrust surface of the thrust washer. In addition, the movable mold plate 2 is disposed on the central axis of the concave portion 2a, the core pin 7 concentric with the concave portion 2a and the ejector pin disposed on the central axis of the core pin 7 (on the central axis of the concave portion 2a). And eight. The core pin 7 is supported by the core pin plate 20. The core pin 7 and the core pin plate 20 are always in a state where a load is applied to the movable mounting plate (not shown) in the mold closing direction by the coil spring 21.

  Further, on the movable mold plate 2, a plurality of ejector pins 9 for taking out the formed thrust washer (formed body) are disposed. The ejector pins 8 and 9 can be advanced and retracted by an ejector rod of an injection molding machine (not shown). In the present invention, "advancing" means advancing in the direction of protruding out of the mold, and "retracting" means advancing in the direction of storing in the mold. The ejector pin 9 is housed in the movable mold plate 2, and the tip end face of the ejector pin 9 faces the cavity 5.

  FIG. 2 is a partially enlarged view of the periphery of the disk gate in the state of FIG. As shown in FIG. 2, the fixed mold plate 3 is disposed flush with the parting line PL, and has a substantially cylindrical nest 10 having an end face 10a that faces the recess 2a and constitutes a part of the cavity 5; The sprue bush 11 is disposed coaxially with the core pin 7 on the central axis of the nest 10. The outer diameter of the annular end surface 10a is larger than the outer diameter of the annular recess 2a. That is, in the mold closing state, a part of the end face 10 a abuts on the end face of the movable mold plate 2. Further, the end face 11a of the sprue bush 11 on the movable mold plate 2 side (the end face facing the core pin 7) 11a and the end face 10a of the insert 10 are flat faces (same faces). Make up a part of The end face 10a forms the other thrust surface of the thrust washer.

  A coil spring 12 is incorporated as an elastic member between the nest 10 and the sprue bush 11 in the fixed mold plate 3, and the coil spring 12 biases the sprue bush 11 in a direction (mold closing direction) away from the parting line PL. It is done. That is, the sprue bush 11 is constantly loaded with a repulsive force against the nest 10. Further, a runner plate 13 is provided on the fixed die plate 3 on the runner stripper plate 4 side, and the sprue bush 11 is fixed to the runner plate 13. The runner plate 13 is provided to be movable in the mold closing direction with respect to the nest 10.

  As shown in FIG. 1, in the runner stripper plate 4, a first sprue 14 provided coaxially with the injection direction of the synthetic resin is disposed between the runner stripper plate 4 and the runner plate 13 of the fixed mold plate 3. A runner 15 provided in the vertical direction of the first sprue 14 in communication with the first sprue 14 is provided in parallel with the injection direction of the molten resin in the sprue bush 11 of the fixed mold plate 3 in communication with the runner 15 The second sprues 16 are respectively provided. Also, the runner stripper plate 4 is connected to the core pin plate 20 by a side plate 22.

  In the mold closed state of FIG. 2, the tip of core pin 7 is arranged at a position slightly retracted from parting line PL. A disc gate 6 is formed between the end face 7a of the core pin 7 and the end face 11a of the sprue bush 11 opposed thereto. The outer diameter of the core pin 7 is substantially the same as the outer diameter of the disk gate 6. The disk gate 6 is in communication with the second sprue 16. The outer peripheral portion of the disk gate 6 is in communication with the inner peripheral portion of the cavity 5 over the entire periphery, and the boundary thereof becomes the gate opening 6a. That is, the disk gate 6 is provided on the inner diameter surface side of the thrust washer. In this configuration, the synthetic resin flowing into the disk gate 6 spreads radially from the entire circumference of the disk gate 6 and is uniformly filled in the cavity 5. Therefore, no weld occurs in a molded article using this injection mold.

  In FIG. 2, the position of the tip of the core pin 7 is retracted from PL in accordance with the thickness (axial length) of the cavity 5. The amount of retraction from the position PL of the tip end of the core pin 7 can be equal to or shorter than the thickness of the thrust washer. The amount by which the tip end surface of the core pin 7 is retracted from PL is the axial length of the gate opening 6a.

  The method for manufacturing a thrust washer using the injection mold of the present invention comprises at least the following three steps (a) to (c). That is, (a) filling a synthetic resin into a cavity formed in an injection molding die via a disc gate to form a molded body, and (b) a gate cutting step for gate cutting in the injection molding die And (c) releasing the mold to release the molded body.

  In the injection molding die of the present invention, the outer peripheral shape of the core pin 7 and the outer peripheral shape of the end face 11a of the sprue bush 11 have the same shape, and in the state where the fixed mold plate 3 and the movable mold plate 2 abut each other. It is characterized in that the sprue bush 11 can be retracted from the parting line PL, and the disc gate 6 can be cut by advancing the core pin 7. In this case, since the outer diameter of the core pin 7, the outer diameter of the disk gate 6, and the outer diameter of the end face 11a of the sprue bush 11 are substantially the same, the fixed mold plate 3 and the movable mold plate 2 meet each other. In this state, when the core pin 7 is advanced in the mold closing direction, the disk gate 6 is pushed to the fixed mold plate 3 side relative to the PL, and is gated by being fitted to the inner peripheral portion of the insert 10. That is, the injection molding die of the present invention is a die capable of gate-cutting the disc gate in a state where the movable die plate and the fixed die plate abut.

  In addition, as shown in FIG. 1, the fixed mold plate 3 has a stop bolt 17 as a limiting means for limiting the backward distance of the sprue bush 11 in the abutting state of the fixed mold plate 3 and the movable mold plate 2. . The stop bolt 17 will be described with reference to FIG. FIG. 3 is a partially enlarged view around the stop bolt in the state of FIG. The stop bolt 17 is a columnar member having a main body 17a and a flange 17b whose one end is enlarged in diameter from the main body 17a. The fixed mold plate 3 has a receiving portion 18 for receiving the stop bolt 17. In this housing portion 18, the stop bolt 17 is housed with its flange portion 17b facing the movable mold plate 2 so that its axial direction and the mold closing direction are parallel. The end 17 c opposite to the flange portion 17 b is connected to the runner plate 13.

  In the mold closed state of FIG. 3, the stop bolt 17 is accommodated movably in the mold closing direction in conjunction with the retraction of the sprue bush 11. Specifically, the stop bolt 17 is accommodated with the end surface on the mold closing direction side of the flange portion 17 b being separated by a predetermined distance D from the flange surface 18 a of the accommodation portion 18. That is, the stop bolt 17 is accommodated in the accommodating portion 18 with a play so as to be movable in the mold closing direction. Thereby, the stop bolt 17 is also moved in the mold closing direction in conjunction with the backward movement of the sprue bush 11 and the runner plate 13, and the end face on the mold closing direction side of the flange portion 17b abuts on the flange surface 18a. Is limited. The predetermined distance D (the amount of play) is set to 0.1 to 3 mm.

  Each process of this manufacturing method is demonstrated using FIGS. 4-7. FIG. 4 shows a molding process, FIGS. 5 and 6 show a gate cut process, and FIG. 7 shows a mold release process.

(A) Molding Step The molding step is a step of filling a molten synthetic resin into a cavity to form a molded body.

  The synthetic resin used in the present invention is not particularly limited as long as it is an injection moldable thermoplastic resin, and can be appropriately adopted according to the conditions of use. Among thermoplastic resins, crystalline resins are preferable. Examples of crystalline resins include polyamide (PA) resin, polyacetal (POM) resin, polyphenylene sulfide (PPS) resin, polyetheretherketone (PEEK) resin, and injection-moldable polyimide (PI) resin. In addition, if necessary, a fibrous reinforcing material such as carbon fiber or glass fiber, or a solid lubricant such as PTFE resin or graphite may be added to the synthetic resin.

  As shown in FIG. 4, the synthetic resin 19 in a molten state injected from the nozzle (not shown) of the injection molding machine passes through the first sprue 14, the runner 15, the second sprue 16 and the disc gate 6 into the cavity 5. After filling and holding pressure, the synthetic resin is solidified by cooling for a fixed time.

(B) Gate Cutting Step The gate cutting step is a step of gate cutting the disk gate in a mold. In this process, the disk gate is cut in a state where the movable mold plate 2 and the fixed mold plate 3 are in abutment with each other.

  The gate cut process will be described based on FIGS. In this process, the abutment surface F between the runner stripper plate 4 and the fixed mold plate 3 allows the integrated resin of the first sprue, the runner and the second sprue to be taken out (these integrated solidified resins are collectively referred to as "runner part"). The distance is released (see FIG. 5). As a result, the runner portion 23 separates from the mold and falls. At this time, the parting line PL remains closed by the parting lock device (not shown). The separated structure of the runner portion 23 from the mold is a general structure of a 3-plate mold.

  In this process, the core pin 7 is advanced at the same time as the runner stripper plate 4 and the fixed template 3 are opened. Specifically, the core pin plate 20 advances the core pin 7 in the mold closing direction, that is, the parting line PL by the coil spring 21 in conjunction with the opening of the abutment surface F between the runner stripper plate 4 and the fixed mold plate 3. (See FIG. 6). At this time, the core pin 7 presses the sprue bush 11 and the runner plate 13 together with the sprue bush 11 and the runner plate 13 in the mold closing direction while sandwiching the resin filled in the disc gate 6 with the end face 11 a of the sprue bush 11. As a result, the sprue bush 11 retreats from PL. Further, since the fixed mold plate 3 and the runner stripper plate 4 are opened, the space between the runner plate 13 and the nest 10 is opened, and a part of the runner plate 13 protrudes from the end face constituting the abutment surface F.

  The stop bolt 17 connected to the runner plate 13 also moves in the mold closing direction in conjunction with the retraction of the sprue bush 11 and the runner plate 13 described above, and the end face of the flange portion 17b on the mold closing direction abuts the flange surface 18a. Contact. By this abutment, the backward movement of the sprue bush 11, the opening of the runner plate 13, and the forward movement of the core pin 7 are limited. That is, the amount of play (the predetermined distance D in FIG. 3) of the stop bolt 17 is substantially the same as the backward distance of the sprue bush 11, the open distance of the runner plate 13, and the forward distance of the core pin 7, respectively. The predetermined distance D may be a distance at which the molded body in a connected state and the disc gate are separated, for example, a distance corresponding to the thickness of the cavity 5 or a distance where the molten resin can be filled in the cavity 5 It is. When the predetermined distance D is thick, a load is applied to the tip of the core pin 7 at the time of gate cutting, and there is a possibility that the replacement time of the core pin may be advanced. Therefore, it is desirable that the predetermined distance D be 2 mm or less.

  In this gate cutting step, the parting line PL is completely restrained by the movable mold plate 2 and the insert 10 having the same inner circumferential dimension as the inner circumferential dimension of the cavity 5 while the resin (molded body) in the cavity 5 is completely restrained. By moving only the disk gate 6 in the mold closing direction by advancing the core pin 7, the molded body and the disk gate move relative to each other. At this time, a shear force is applied to the gate opening 6 a by the outer peripheral surface of the core pin 7, and as a result, the gate opening 6 a is cut from the resin in the cavity 5 by the core pin 7. The inner diameter surface of the thrust washer is formed by cutting the disk gate 6 with the core pin 7. That is, the inner diameter surface of the thrust washer is formed by the core pin 7 advancing toward the stationary mold plate 3. In lathe processing, which is a general removal step of a disk gate, marks along the circumferential direction are formed on the inner diameter surface of the thrust washer, but in the manufacturing method of the present invention, gate cutting is performed by pressing and cutting in a mold There is no mark by this lathe processing.

(C) Release step The release step is a step of removing the molded body by opening the fixed mold plate and the movable mold plate (see FIG. 7). In this process, the movable mold plate 2 is released from the fixed mold plate 3 in the mold opening direction by releasing the parting lock device. That is, the parting line PL is opened. Further, immediately after the mold opening, the ejector pin 8 disposed in the axial center of the core pin 7 and the ejector pin 9 disposed in the movable mold plate 2 are pushed forward by the ejector rod and advanced. By this advance, the disc gate portion 24 stuck to the tip of the core pin 7 and the thrust washer 31 which is an injection molded body are taken out of the mold.

  After the thrust washer 31 and the disc gate portion 24 are taken out from the injection molding die 1, the space between the movable plate 2 and the fixed plate 3 and the space between the fixed plate 3 and the runner stripper plate 4 are closed. Injection molding takes place.

  As described above, the thrust washer 31 as shown in FIG. 8 is manufactured by the steps (a) to (c). Since the injection mold of the present invention can be gate-cut in the mold as described above, it is possible to omit the process of removing the disc gate such as lathe after injection molding. Thereby, simplification of a manufacturing process, shortening of a manufacturing time, cost reduction, etc. can be achieved. In addition, since the disk gate system is adopted, welding does not occur in the molded thrust washer, so that the reduction in strength and the reduction in surface smoothness due to the welding can be prevented.

  The injection mold of the present invention is configured as shown in FIG. 1 as long as the sprue bush can be retracted from the parting line PL in the above-described mold closed state and the disc gate can be cut by advancing the core pin. It is not limited to the mold shown in 3.

  The thrust washer obtained by the injection molding die of the present invention is used, for example, in a planetary gear device used in a traveling device such as a hydraulic crane, a turning device, and a construction machine such as a rope winch for a hydraulic crane. In a planetary gear, a thrust washer is used to be interposed between a planetary gear and a carrier. In this case, each of the two thrust surfaces of the thrust washer becomes a sliding surface with the planetary gear and the carrier.

  In the injection mold of the thrust washer according to the present invention, since the disc gate can be omitted while removing the disc gate such as lathe after injection molding, the manufacturing process is more efficient and the manufacturing cost is excellent. It can be widely used as an injection mold for thrust washers.

1 Injection molding mold 2 Movable mold plate
3 Fixed template 4 Runner stripper plate 5 Cavity 6 Disc gate 7 Core pin 8 Ejector pin (Ejection pin)
9 Ejector pin (Ejection pin)
DESCRIPTION OF SYMBOLS 10 Nest 11 Sprue bush 12 Coil spring 13 Runner plate 14 1st sprue 15 runner 16 2nd sprue 17 Stop bolt (restriction means)
18 accommodation portion 19 synthetic resin 20 core pin plate 21 coil spring 22 side plate 23 runner portion 24 disc gate portion 31 thrust washer 32 inner diameter surface 33 outer diameter surface 34 cutaway portion 35 groove

Claims (5)

A hollow disk-shaped thrust washer injection molding die of a three-plate die structure comprising a movable die plate, a fixed die plate and a runner stripper plate,
The injection molding mold is formed by injection molding a synthetic resin through a disc gate provided on an inner peripheral portion of the cavity in an annular cavity formed by abutting the fixed mold plate and the movable mold plate. It is a mold to
The movable template includes an annular recess which constitutes a part of the cavity, a core pin which is concentric with the recess and which is disposed on the central axis of the recess, and which is disposed on the central axis of the core pin With an ejector pin,
The fixed mold plate is disposed flush with the abutment surface with the movable mold plate, and has a nest having an end face facing the recess and constituting a part of the cavity, and on a central axis of the nest, And a sprue bush coaxially disposed with the core pin,
The outer peripheral shape of the core pin and the outer peripheral shape of the surface of the sprue bush facing the core pin have the same shape,
The disc gate is formed between the core pin and the sprue bush in an abutting state in which the fixed mold plate and the movable mold plate are abutted, and in the abutting state, the sprue bush is in the abutting surface An injection mold for a thrust washer, which is retractable from the disc and capable of cutting the disc gate by advancing the core pin.   The injection mold for a thrust washer according to claim 1, wherein the core pin advances in the mold closing direction and the sprue bush retracts in the abutting state.   The injection mold for a thrust washer according to claim 2, wherein the fixed mold plate has a limiting means for limiting the retraction distance of the sprue bush in the abutting state. The limiting means is a columnar member having a main body portion and a flange portion expanded in diameter from the main body portion,
The fixed mold plate has a housing portion for housing the restriction means, and in the housing portion, the restriction means is accommodated movably in the mold closing direction in conjunction with the retraction of the sprue bush, the restriction 4. The injection molding of a thrust washer according to claim 3, wherein an end face on the mold closing direction side of the flange portion abuts on the accommodation portion with the movement of the means, thereby limiting the retraction distance of the sprue bush. Mold.   The injection molding die for thrust washer according to any one of claims 2 to 4, wherein the core pin is advanced at the same time as the runner stripper plate and the fixed mold plate are opened. .

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